96 New York State Museum 



tunicates are fastened by a fusion of the area of attach- 

 ment with the surface to which they are attached by some 

 chemical reaction. Shore turbellarians, (Planarian or 

 Flat Worms) have adhesive papillae at the pointed hind 

 end or sometimes all over the body and the shape of the 

 body also is designed to withstand the shock of waves. 

 Nudibranchs, or naked mollusks, have mucus chiefly on 

 the foot, especially at the posterior end, but they also 

 have a string of mucus attached to the end of the tail by 

 which they are anchored. 



The above are some of the special powers of adhesion 

 adopted by shore animals to withstand the impact of the 

 waves. In addition, certain shore animals have a form 

 of body adapted to minimizing friction. The turbel- 

 larians cited above, some of which are leaflike, are one 

 example and the flattened nudibranchs another. Some 

 species are incrusting forms and solve the problem in this 

 way. There are incrusting plants, such as the incrusting, 

 stony Lithothamnion and incrusting sponges, hydroids, 

 bryozoans, compound tunicates etc. Shore crustaceans 

 show some influence in a flattening of the body. The 

 amphipods, exemplified by the common Gammarus or 

 Scud, show a lateral flattening, and the little isopods show 

 a dorso-ventral flattening. Dorso-ventral flattening is 

 especially characteristic of the shore crabs. The limpet 

 form is the common shape along the shore, and is a 

 direct result of the environment. There are numerous 

 gastropods which are squat forms. The shells have a 

 low spire or are devoid of a spire and there is little or no 

 ornamentation. Studies of shells of certain species have 

 brought out the fact that the character of shells varies 

 with the type of situation; there is a direct relation be- 

 tween the form of the shell and the degree of exposure. 



